QuoteI guess that a good charge controller is supposed to switch off after the saturation phase anyway.
Well that's the issue here - we are guessing, and no-one seems to know why some manufacturers (who, after all, would probably prefer not to make out that their product might be a bit iffy) state that the phone shouldn't be left on extended charge. If the charge controller, however that's implemented, could just consider the battery done and turn it all off, there would be no need for such warnings, would there? Indeed, does Apple have similar warnings despite apparently being able to control the charge from software?
I once replaced the degraded battery in an iPhone 6 (my obsolete backup phone) with a new battery (replaced at an Apple Store, so zero chance of counterfeit battery) and after a year of being left plugged in, the battery swelled.
I think there needs to be further explaination here. The iPhone 6 series were riddled with problems. Premature failure of the LCD/digitiser, to battery issues (as you have found out). The iPhone 6 were just a garbage phone with a very high failure rate. Not sure why, but when I was doing digital forensics examinations on an iPhone 6 that wouldn't boot, first thing that got removed was the battery and we powered them up using external power.
if the device mismanaged the charging it would be obvious fairly early on in the devices life.
Has anyone really evidence that a smart phone battery will last longer than roughly 500 charge/discharge cycles (or say 1-2 years of daily discharge/recharge) if it is not kept plugged-in after the battery has reached 100% SOC? I guess that a good charge controller is supposed to switch off after the saturation phase anyway.
QuoteI guess that a good charge controller is supposed to switch off after the saturation phase anyway.
Well that's the issue here - we are guessing, and no-one seems to know why some manufacturers (who, after all, would probably prefer not to make out that their product might be a bit iffy) state that the phone shouldn't be left on extended charge. If the charge controller, however that's implemented, could just consider the battery done and turn it all off, there would be no need for such warnings, would there? Indeed, does Apple have similar warnings despite apparently being able to control the charge from software?
Charge and maintain your iPhone battery
Learn about charging the battery in your iPhone and how you can prolong your battery's lifespan.
About your battery's lifespan
A battery’s lifespan is related to its chemical age, which is more than just the length of time since the battery was assembled. A battery’s chemical age results from a complex combination of several factors, including temperature history and charging pattern. All rechargeable batteries are consumable components that become less effective as they chemically age. As lithium-ion batteries chemically age, the amount of charge they can hold diminishes, resulting in reduced battery life and reduced peak performance.
Learn more about iPhone battery and performance
Learn how to maximize battery performance and lifespan
How charging affects your battery
For most customers, the battery in your iPhone should last the whole day. You can charge your iPhone every night even if the battery isn't fully depleted.
iPhone automatically stops charging when the battery is fully charged, so it's safe to keep your iPhone connected to a charger overnight. Charging resumes automatically if your battery level drops below 95 percent.
When possible, unplug your iPhone after it has fully charged. By default, your iPhone uses Optimized Battery Charging. To improve your battery's lifespan, Optimized Battery Charging reduces the time that your iPhone spends fully charged. It fully charges your iPhone just in time for you to use it.
A battery warms up as it charges, which can reduce its lifespan. To reduce the effect of heat and prevent overheating, iPhone gradually reduces the charging current as the battery approaches full charge.
Learn more about Optimized Battery Charging
How temperature affects your battery
iPhone is designed to perform well in a wide range of ambient temperatures, with 62° to 72° F (16° to 22° C) being the ideal comfort zone.
Avoid using or charging your device in ambient temperatures higher than 95° F (35° C), which can permanently reduce battery lifespan.
When using your device in a very cold environment, you might notice a decrease in battery life. This condition is temporary; when the battery’s temperature returns to its normal operating range, its performance will return to normal.
Software might limit charging above 80 percent when the recommended battery temperatures are exceeded.
Learn more about how temperature can affect your iPhone
How Wi-Fi and Bluetooth affect your battery
Wi-Fi and Bluetooth are designed to draw minimal power from the battery when they aren't connected to a network or accessory. For the best experience on your iPhone, keep Wi-Fi and Bluetooth turned on.
Some features might not work if you turn off Wi-Fi or Bluetooth
Learn how to check our your battery health and other information about your battery
Published Date: November 15, 2023
About 80% Limit with iPhone 15 models
With iPhone 15 models, you can choose between Optimized Battery Charging, 80% Limit, and None.
When you choose 80% Limit, your iPhone will charge up to about 80 percent and then stop charging. If the battery charge level gets down to 75 percent, charging will resume until your battery charge level reaches about 80 percent again.
With 80% Limit enabled, your iPhone will occasionally charge to 100 percent to maintain accurate battery state-of-charge estimates.
And I am sure Apple, Samsung, Google will have similar statements in their manuals to cover themselves.
On the off-chance I'm wrong: I would have thought that the review from your device would mention battery issues - if the device mismanaged the charging it would be obvious fairly early on in the devices life.
The fixed 80% is new, and I’m not sure why they wouldn’t enable that software option for older devices, too.
if it was normal for a phone battery to completely die by sitting two months plugged in, we would be seeing a lot of complaints, and N would be in millions, not 1.
QuoteI guess that a good charge controller is supposed to switch off after the saturation phase anyway.
Well that's the issue here - we are guessing, and no-one seems to know why some manufacturers (who, after all, would probably prefer not to make out that their product might be a bit iffy) state that the phone shouldn't be left on extended charge. If the charge controller, however that's implemented, could just consider the battery done and turn it all off, there would be no need for such warnings, would there? Indeed, does Apple have similar warnings despite apparently being able to control the charge from software?
If you don’t even know why you were removing the battery and powering it externally, I hardly consider that a useful anecdote (never mind a data point).
if it was normal for a phone battery to completely die by sitting two months plugged in, we would be seeing a lot of complaints, and N would be in millions, not 1.
Absolutely! But that's a straw man and you know it - no-one has suggested anything like that timescale.
they know full well their product is crap, the battery is going to swell and the user isn't going to follow their instructions, therefore they can turn around to the user and say "you didn't follow instructions" while denying any warranty claims.
I mean, it was literally* here: https://www.eevblog.com/forum/chat/battery-overcharing/msg5241633/#msg5241633
*) not two, but "a few", sorry.
they know full well their product is crap, the battery is going to swell and the user isn't going to follow their instructions, therefore they can turn around to the user and say "you didn't follow instructions" while denying any warranty claims.
OK, so you now agree that there may be a battery issue (not necessarily swelling - reduced life is sufficient) if the device is left on charge past when it is fully charged?
No-one has ever suggested that plugging a phone in every evening to charge overnight would cause a problem. Millions of people do that, and it evidently is a normal and expected way to use a phone.
What is being suggested is that if you take a phone, plug it into the charger, and leave it like that without unplugging it for several months, then that might cause a problem.
This is obviously hard to gather data for, since very few people do that with a phone. The whole point of a phone is that you carry it with you.
Siwastaja says that in theory that shouldn't cause a problem. What I say is that we don't know if every sample of a battery, and every embodiment of a battery and charging system out there, is without flaw in design or manufacture.
Enough people have reported problems with leaving a device plugged in and on charge for days, weeks, months continuously that it might be a problem. I think there is enough doubt in this area that it is not worth taking the risk.
No-one has ever suggested that plugging a phone in every evening to charge overnight would cause a problem. Millions of people do that, and it evidently is a normal and expected way to use a phone.
What is being suggested is that if you take a phone, plug it into the charger, and leave it like that without unplugging it for several months, then that might cause a problem.
It is just way more likely that your battery was already in bad condition and not specifically killed by what you did, but without forensics, we are guessing.
The fixed 80% is new, and I’m not sure why they wouldn’t enable that software option for older devices, too.
Because they'd get reamed for it. Recall what happened why they slowed phones down to make the batteries last a bit longer.
Which leads me to...
Suppose you (as a manufacturer) can control the battery charge in an on/off fashion. Once it gets up to whatever you consider fully charged you can flip the switch and the charge is turned off. Being clever, you can arrange that the battery is just fully charged when the user wakes up in the morning, either from monitoring their usual wake time or by looking at the set alarm. You can put off charging until the exact time before wakeup that it will take to charge, or you can wait until it's at 100% (or the preferred level), turn it off and then just before wake give it a couple of minutes to make up for what's since drained.
Magic. But what if the user has irregular hours and/or doesn't use the phone alarm? You could wait until full charge and then turn it off, but you wouldn't know when to do the last moment top up. The user could be taking it away in the next minute or they might've gone off on holiday, and you won't know until the cable is pulled. Is the top up important? I think it is, because if the user puts it on charge and then goes to use it and finds it at only 95% they will get a bit annoyed. Especially if it's habitual.
OK, so you can't afford (reputation-wise) to take it off charge unless you know how long it will be on charge (cf. alarm, etc). You could fake the charge - if the actual charge is 95% when the user pulls the cable you could say it's 100% and they'd never know, but then you'd have to fake the fall in charge during use because the user would notice an unaccountable step. I think Apple have tried something like this in the past and got roundly told off.
No-one has ever suggested that plugging a phone in every evening to charge overnight would cause a problem. Millions of people do that, and it evidently is a normal and expected way to use a phone.
What is being suggested is that if you take a phone, plug it into the charger, and leave it like that without unplugging it for several months, then that might cause a problem.
This is obviously hard to gather data for, since very few people do that with a phone. The whole point of a phone is that you carry it with you.
No-one has ever suggested that plugging a phone in every evening to charge overnight would cause a problem. Millions of people do that, and it evidently is a normal and expected way to use a phone.
What is being suggested is that if you take a phone, plug it into the charger, and leave it like that without unplugging it for several months, then that might cause a problem.
It would need to be a very weird "feature", I'd say bug, because overnight charging already is a significant %, nearly 50% for some people, so upping that to 100% is not going to be a massive difference. But of course, anything can happen, faulty products and weird corner cases pop up every now and then, especially for something which does not see much testing. Although I think you might underestimate the number of people who use the phone plugged in for nearly 24/7. Think about those who drive for a living (bus, taxi, truck drivers etc.) who plug the phone in the car, and also for the night. It might be plugged in for 22 hours a day.
But of course, there might be a plain old bug which triggers when the phone has been continuously plugged in for, let's say 24.855 days, after which a signed 32-bit integer counting milliseconds wraps around, and maybe triggers increase of charge voltage from 4.20V to 4.40V. Or something like that. It is just way more likely that your battery was already in bad condition and not specifically killed by what you did, but without forensics, we are guessing.